The Internet Protocol television (IPTV) service solves the problem that users are constrained by the schedule of television programs, meets the demands of users for watching television programs freely, and provides powerful interactive functions.
During the use of the IPTV service, a television terminal first needs to access a broadband network with a set-top box (STB), and then the STB sends, to an IPTV server, a request to access an IPTV system, and the IPTV server authenticates and authorizes a user, and returns a registry success message when the authentication is successful. After the successful registry of the user, the STB can obtain, from the IPTV server, a media program channel information list. The STB sends, according to the channel list, an Internet Group Management Protocol (IGMP) packet request corresponding to a multicast group address to apply, to a network device, for joining a multicast channel to which a media stream belongs. Subsequently, after the data stream corresponding to the channel reaches the user terminal, the programs can be normally watched.
Conventionally, when virus attack or an illegally-constructed IGMP packet request occurs on a terminal device on a user side, the multicast table of an intermediate network device might be exhausted, resulting in that legal users cannot operate normally.